"Our missile power today far surpasses that of the 12-day war," Araghchi said in the Western city of Hamedan on Wednesday according to official media. "The enemy in the recent 12-day war failed to achieve all its objectives and was defeated."
The United States held five rounds of negotiations with Tehran over its disputed nuclear program earlier this year, for which President Donald Trump set a 60-day ultimatum.
When no agreement was reached by the 61st day Israel launched a surprise military offensive on June 13, followed by US strikes on June 22 targeting key nuclear facilities in Isfahan, Natanz and Fordow.
"In this war, the skies over the Zionist regime were under Islamic Republic control, and no defensive layer could stop our missiles," Araghchi said.
A ceasefire ended the 12-day conflict, but inspections of damaged sites remain suspended under Iranian law.
Hundreds of military personnel and civilians were killed in the Israeli airstrikes. Tehran responded with over 500 ballistic missiles and 1,100 drones, inflicting heavy casualties and widespread destruction, killing 32 Israeli civilians and one off-duty soldier.
On Sunday, Araghchi accused Israel of misleading Washington with what he called a fabricated nuclear threat and urged President Donald Trump to change course.
He said Israel and the US attacked Iranian nuclear sites under "false pretenses" and cited comments from the UN atomic watchdog and Oman's foreign minister confirming that Iran was not developing nuclear weapons.
Iran's Supreme Leader Ali Khamenei on Monday ruled out any cooperation with the United States, saying every US president had demanded “Iran’s surrender” but failed.
Iran denies seeking nuclear arms and says its program is peaceful.